ABSTRACT
Thermoelectric transport properties of Janus monolayers M2P2S3Se3 (M = Zn and Cd) are investigated by the first-principles based transport theory. The Zn2P2S3Se3 and Cd2P2S3Se3 monolayers are indirect-gap semiconductors. The high polarizability of M-Se/S bonds in the MS3Se3 distorted octahedrons leads to anharmonic phonon behavior, which produces an intrinsic lattice thermal conductivity (κl) as low as 1.06 and 1.99 W m-1 K-1 at 300 K for Zn2P2S3Se3 and Cd2P2S3Se3 monolayers, respectively. The lower κl of the Zn2P2S3Se3 monolayer is mainly attributed to more pronounced flat modes of the phonon dispersion in a frequency range of 1-1.7 THz caused by the softer Zn-Se/S bonds. The polar optical phonon scattering of carriers surprisingly plays a dominant role in carrier transport of both the monolayers, which greatly suppresses the electrical conductivity and thereby the power factor by about an order of magnitude. The predicted figure of merit (zT) increases monotonically with the temperature at the optimal carrier density, and at the operating temperature of 1200 K, it reaches an optimal value of 0.86 at an optimal electron density of â¼1.5×1013 cm-2 for the n-type Zn2P2S3Se3 monolayer and 0.30 at an optimal electron density of â¼7×1012 cm-2 for the n-type Cd2P2S3Se3 monolayer.
ABSTRACT
The thermoelectric transport properties of two-dimensional (2D) layered NaCuX (X = S, Se) are investigated by employing first-principles based Boltzmann transport theory. Single quintuple NaCuX layers have a relatively large Seebeck coefficient (S), electrical conductivity (σ) and hence power factor (PF = S2σ) for a p-type heavy doped region due to the valence band degeneracy. The largely reduced σ by dominant polar scattering leads to a PF up to 0.27 and 0.84 mW m-1 K-2 at 1200 K for p-type NaCuS and NaCuSe monolayers, respectively. The high polarizability of the Cu-X bonds in the CuX4 tetrahedra leads to anharmonic phonon behavior which produces an intrinsic lattice thermal conductivity (κl) as low as 1.03 and 0.75 W m-1 K-1 at 300 K for NaCuS and NaCuSe, respectively. The predicted figure of merit (zT) increases monotonically from around 0.25 at 300 K to 2.01 at 1200 K at an optimal carrier density of around 1 × 1013 cm-2 for p-type NaCuSe and from around 0.09 at 300 K to 1.15 at 1200 K at an optimal carrier density of around 1 × 1014 cm-2 for p-type NaCuS. These findings indicate that the NaCuS, especially NaCuSe, monolayers are promising 2D thermoelectric materials persisting at high temperature.
ABSTRACT
Tumor necrosis factor-like weak inducer of apoptosis (TWEAK) is a well known multifunctional cytokine extensively distributed in cell types and tissues. Accumulating evidence has shown that TWEAK binding to the receptor factor-inducible 14 (Fn14) participates in diverse pathologic processes including cell proliferation and death, angiogenesis, carcinogenesis and inflammation. Interestingly, alterations of intracellular signaling cascades are correlated to the development of respiratory disease. Recently, a several lines of evidence suggests that TWEAK in lung tissues are closely associated with these signaling pathways. In this review, we explore if TWEAK could provide a novel therapeutic strategy for managing respiratory disease in general and pulmonary arterial hypertension (PAH), obstructive sleep apnea syndrome (OSAS), asthma, idiopathic pulmonary fibrosis (IPF), chronic obstructive pulmonary disease (COPD) and non-small cell lung cancer (NSCLC), specifically.
